A new paint developed by researchers at Purdue University is the coolest — literally.
When Xiulin Ruan, a professor of mechanical engineering at the school, and his graduate students began working on this project seven years ago, they didn’t set out to invent a new paint color. They were looking for a way to conserve energy, and combat climate change. They found that paint could do exactly that.
And so Ruan and his team created the world’s whitest paint — a It recently received the titleGuinness World Records books a status that was never achieved.
However, this paint can do more than just set world records. It is a breakthrough in sustainability. It could reduce or eliminate the need to air conditioners and the energy required to power them.
“The impact of this paint, it’s good for trying to alleviate global warming, the urban heat island effect and the electricity crisis,” said Xiangyu Li, a postdoctoral researcher at the Massachusetts Institute of Technology who worked on this project as a Ph.D. student in Ruan’s lab. “But the part I like the best is that it could directly impact peoples’ electricity bills, and that’s something everyone can relate to.”
Reflects almost 100% light
Developing the formula for this paint wasn’t easy. The multiple-year study builds on efforts to create a cooling paint as an alternative to traditional air conditioning that dates back to the 1970s.
Researchers considered more than 100 materials before narrowing down their choices to 10. The lab then tested approximately 50 different formulations of each material.
“I started looking at every white material in my daily life,” Li said.
That’s when they found barium sulfate. The concentration and size of the barium sulfurate compound are key factors in the paint’s composition.
The paint contains a very high level of the compound. It is also used to make white cosmetics and photo papers. It also contains barium sulfate particles that come in different sizes.
Most white paints have one single particle size that reflects the visible portion of the solar spectrum, but they absorb more ultraviolet and infrared light, according to Joseph Peoples, a Ph.D. candidate in Purdue’s School of Mechanical Engineering who also worked in Ruan’s lab.
“The largest difficulty was making the paint as reflective as possible for the entire solar spectrum,” Peoples said.
Peoples stated that the size of each barium-sulfate particle affects how much light it scatters. The paint can scatter more of the full spectrum of light if it has a wider range in particle sizes.
According to researchers, this whitest white paint may be the closest comparable. Vantablack, the darkest black paint that absorbs 99.9% of visible sunlight. The paint that Ruan’s lab landed on reflects up to 98.1% of sunlight, According to the research. This compares to other highly reflective paints that reflect 80 to 90% light.
Because Ruan’s paint reflects almost all incoming sunlight, it’s not taking on any energy. Then it goes a step further, emitting thermal energy into outer-space beyond Earth’s atmosphere, meaning it sends out more heat than it takes in.
“Let’s say it is a dry sunny day outside and the temperature is 85 degrees Fahrenheit,” a surface covered with the paint from Purdue “will be around 75 degrees Fahrenheit,” Peoples said. “The paint cools itself below ambient, creating free refrigeration, with no electricity input at all.”
More powerful than central air conditioning
This white paint can lower the temperature of buildings that have been painted with it. It also lowers the interior temperatures. If buildings aren’t heating up from sunlight, then that lowers the need to switch on their air conditioning as high or removes it entirely.
“If you were to use this paint to cover a roof area of about 1,000 square feet, we estimate that you could get a cooling power of 10 kilowatts,” Ruan said in a statement. “That’s more powerful than the central air conditioners used by most houses.”
Ruan is a painter and his schedule didn’t allow him to speak to IndyStar.
While the difference of 98% to 90% might not seem like a lot, Li said that before a building was absorbing 10% of sunlight and now it’s only absorbing 2% – “so it’s actually absorbing five times less, which gives major cooling benefits.”
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Most people think of reducing carbon emissions by reducing carbon emissions in the transportation sector and industry. The study found that buildings account for almost 40% of the annual energy-related CO2 emission in the world. United Nations climate report. According to the city, 66% of Indianapolis’s greenhouse gas emissions are caused by buildings. Most of those emissions result from building operations, such as cooling or heating.
Therefore, cutting down on cooling means using less energy produced by fossil fuels such as coal and natural gas, which could lead to reduced climate change-causing carbon emissions.
“I think the white paint discovery has, over the longer term, potentially some big implications,” said Jeff Dukes, the executive director of the Purdue Climate Change Research Center. “In many parts of the world where we want to be cooling our buildings for most of or all of the year for comfortable spaces, this could mean big potential energy savings.”
Whitest paint can also help to reduce the Urban heat island effectPeoples estimates that it is. Urban heat islands are formed when cities replace natural land cover with buildings, pavements, and other materials that absorb and retain heat. This can lead to increased energy use, pollution, and heat-related diseases.
Climate change is causing more severe and frequent heat waves. According to research out of Dukes’ center, Indiana could see as much as 30 more days above 95 degreesBy the middle of the century
The latest UN climate change report issued a “code red for humanity” when it comes to the climate crisis, and stressed the importance of taking rapid action to curb emissions. Dukes suggested that this paint could only be one tool in a larger toolbox.
For the everyday American, the paint also could make a big difference for their pockets, Li said, because it’s essentially creating free air conditioning.
Paint can save a house with a single story measuring approximately 1,000 square feet about $1 per day. This is in addition to the cost of air conditioning. This is a savings of about $30 per month or almost $360 per year in electricity costs.
“The paint has the benefits of saving on electric bills and at the same time contributing to saving the earth,” Li said, “it connects with everyone.”
Marketing the paint
The researchers believe that this paint can be used in a variety of ways. The most obvious is on commercial as well as residential buildings, both on their roofs, which face direct sunlight, and the side walls.
But the researchers add that it could even go as far as being applied to road surfaces or cars to help cool the earth’s surface on an even larger scale.
The paint was submitted to a patent application by the team. The paint is currently being tested to ensure it is ready for commercialization. Ruan and his team are currently working with a commercial company in order to ensure that the paint can withstand the elements and meets outdoor paint’s reliability requirements.
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Li said that there is no set date for when the paint will be available in stores, but it will likely take a few years before customers can purchase it at their local hardware shop. Purdue paint will be cheaper than other outdoor paints and it will use a similar fabrication process, so it should not be difficult to produce.
“Our goal is that if we can push it to the market, it will be like buying any other white paint,” Li said. “The most important way we can make the most of scientific innovation in this field is to make it so that more and more people can use it.”
That’s why Ruan and his graduate students loved the idea of a paint: It’s approachable and easy.
However, they acknowledge that it will not be easy to convince people to use white paint. Many homeowners may not be used seeing white walls, especially from a residential standpoint. They might also want their house to stand apart from other houses on their street.
“Already people aren’t using white paint everywhere to try to keep buildings cool,” Dukes said, “so it’s a question of how many people are going to use it?”
According to the city of Indianapolis, it has ideas about how it can increase such adoption. Morgan Mickelson, executive director at the Sustainability Office, stated that the office is always looking to find ways to make residents use these types of incentives.
A similar ordinance was also adopted by city officials. Benchmarking and Transparency OrdinanceTo improve the energy efficiency and water efficiency of Indianapolis buildings. Building owners who participate in the program must measure how much water and energy their buildings use each year and report it annually. They can then work with the city on ways to reduce their water and energy consumption.
Mickelson stated that she believes this paint, when it is available, could be a key way to achieve that.
“Our built environment has one of the largest opportunities for reducing greenhouse gas emissions significantly,” she said, adding that the city will try to find ways to use this paint on its own buildings when it’s available.
“To have the whitest white paint from Purdue University is so exciting,” Mickelson added, “especially to be an Indiana institution leading the charge on this type of work.”
Sarah Bowman, IndyStar reporter, can be reached at 317-444-6129. sarah.bowman@indystar.com. Follow her on Twitter Facebook: @IndyStarSarah. Connect with IndyStar’s environmental reporters: Join Facebook: The Scrub.
The Nina Mason Pulliam Charitable Trust generously supports IndyStar’s environmental reporting projects.
